A restore method is known which restores a system, a disk, or a database in which a failure has occurred.
When restoration is performed via a network, it is time-consuming, and a business operation cannot recover until the restoration is completed.
Thus, a method is known which fixes/restores data content of a system to a reserved disk without stopping the system.
A method is also known which manages the status of a copy operation by using a table and accesses data without stopping the system.
However, in the above-described method, for example, since a data access method is changed by referencing boundary information that indicates the end position of the storage region where data storing is completed, it is not possible to directly update or reference data in the region of the reserved disk where restoration is not completed. Therefore, there is a problem that the same region must be re-restored later.